Re: [PATCH 04/23] sim/erc32: Add FPU support on x86_64 hosts.

Jiri Gaisler
2015-02-19T20:45:38Z

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On 02/17/2015 10:05 AM, Mike Frysinger wrote:
> On 17 Feb 2015 08:44, Jiri Gaisler wrote:
>> * float.c (get_accex) access FPU control and status words on x64
>
> shouldn't you gut this file and use <fenv.h> instead for a portable method ?
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/fenv.h.html
>
> at the very least, you could cut over to <fpu_control.h> ...
> -mike
>

I will switch to fenv.h, but this will produce less accurate results
on Intel hardware. double on SPARC V8 has 53-bit mantissa while Intel has
both 53- and 64-bit, and 64-bit is default. To get accurate SPARC V8 FPU
operations, the Intel FPU should be switched to 53-bit, but the fenv.h
does not have an API for this. I guess we will have to live with that ...

Jiri.

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